<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Canvas</title>
    <style type="text/css">
        body {
            text-align: center;
            padding-top: 20px;
        }
        canvas {
            box-shadow: 0 0 10px #333;
            margin: 0 auto;
        }
    </style>
</head>
<body onload="draw()">
<canvas id="canvas" width="800" height="600">
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</canvas>

<script>
    function draw() {
        var canvas = document.getElementById("canvas");
        if (canvas.getContext) {
            var ctx = canvas.getContext('2d');

            var img = new Image();
            img.src = 'img.jpg';

            img.onload = function () {
                ctx.beginPath();
                ctx.arc(400, 300, 100, 0, Math.PI * 2);
                ctx.fill();
                ctx.clip();

                ctx.drawImage(this, 150, 110);
            }
        }
    }
</script>
</body>
</html>
